/**
 * 纯文本 URL 切分（QQ 风格：识别 http(s):// 与 www.）
 * 仅产出 http/https，拒绝其它协议。
 */

const URL_RE = /(?:https?:\/\/|www\.)[^\s\u4e00-\u9fff<>"'`]+/gi;

/** 常见尾随标点从 URL 剥离（中英） */
const TRAIL_PUNCT = /[.,;:!?。，；：！？、)\]}》〉』」"'`]+$/;

export type LinkifyPart =
  | { type: "text"; value: string }
  | { type: "url"; value: string; href: string };

function toHref(raw: string): string | null {
  const href = /^www\./i.test(raw) ? `https://${raw}` : raw;
  try {
    const u = new URL(href);
    if (u.protocol !== "http:" && u.protocol !== "https:") return null;
    return u.href;
  } catch {
    return null;
  }
}

function peel(raw: string): { core: string; trail: string } {
  const m = raw.match(TRAIL_PUNCT);
  if (!m) return { core: raw, trail: "" };
  return { core: raw.slice(0, -m[0].length), trail: m[0] };
}

/** 将纯文本切成文本段与可安全打开的链接段 */
export function linkifyParts(text: string): LinkifyPart[] {
  if (!text) return [];
  const parts: LinkifyPart[] = [];
  let last = 0;
  URL_RE.lastIndex = 0;
  let m: RegExpExecArray | null;
  while ((m = URL_RE.exec(text)) !== null) {
    if (m.index > last) {
      parts.push({ type: "text", value: text.slice(last, m.index) });
    }
    const { core, trail } = peel(m[0]);
    const href = core ? toHref(core) : null;
    if (href && core) {
      parts.push({ type: "url", value: core, href });
      if (trail) parts.push({ type: "text", value: trail });
    } else {
      parts.push({ type: "text", value: m[0] });
    }
    last = m.index + m[0].length;
  }
  if (last < text.length) parts.push({ type: "text", value: text.slice(last) });
  return parts.length ? parts : [{ type: "text", value: text }];
}